While many features have been provided in the past to maximize the heat transfer between cooling air and the airfoil, the design of gas turbine airfoils is nevertheless the subject of continuous improvements so as to further increase cooling efficiency without significantly increasing pressure losses inside the airfoil. An example of such area is the concave or pressure side of an airfoil, near the trailing edge. For instance, U.S. Pat. Nos. 6,174,134 and 6,607,356 disclose various structures intended to introduce turbulence in this region to enhance cooling efficiency, albeit at the price of an added pressure drop. Despite these past efforts, there is still a need to improve the cooling efficiency in some areas of airfoils.